Khan.scratchpad.disable(); Vanessa sells magazine subscriptions and earns $$10$ for every new subscriber she signs up. Vanessa also earns a $$20$ weekly bonus regardless of how many magazine subscriptions she sells. If Vanessa wants to earn at least $$90$ this week, what is the minimum number of subscriptions she needs to sell?
Solution: To solve this, let's set up an expression to show how much money Vanessa will make. Amount earned this week $=$ $ $ Subscriptions sold $\times$ Price per subscription $+$ Weekly bonus Since Vanessa wants to make at least $$90$ this week, we can turn this into an inequality. Amount earned this week $\geq $90$ Subscriptions sold $\times$ Price per subscription $+$ Weekly bonus $\geq $90$ We are solving for the number of subscriptions sold, so let subscriptions sold be represented by the variable $x$ We can now plug in: $x \cdot $10 + $20 \geq $90$ $ x \cdot $10 \geq $90 - $20 $ $ x \cdot $10 \geq $70 $ $x \geq \dfrac{70}{10} = 7$ Vanessa must sell at least 7 subscriptions this week.